For 32 years at the Manhattan DA’s cavernous case archives, a pair of semen-stained green panties has sat – vouchered, sealed in plastic and forgotten – inside a red paper envelope.

But prosecutors now say that for those three decades, the panties held a vital secret: the DNA profile of a fiend who went on to pull knives and guns on 24 other women in brutal sex attacks in New York City, Maryland and New Jersey.

The panties were only taken from their wrapping and tested by the city medical examiner this month, after an amazing collision of chance, modern technology and good detective work.

Prosecutors in three states are now hoping that the 32- year-old underwear will seal the fate – and the prison door – for an Arabic scholar, divorced father of two and admitted rapist named Fletcher Anderson Worrell.

“There are a lot of women in the Washington, D.C., area and in New Jersey who can rest easy now,” Manhattan DA Robert Morgenthau said yesterday, in announcing the DNA hit linking Worrell, 58, to a sickening career of attacks.

Investigators allege the following:

On June 26, 1973, Worrell, then 26, climbed through the unlocked West 21st Street bedroom window of a 25-year-old Manhattan actress and artist, raping her, slashing her neck, and leaving behind the tell-tale semen stains. He was promptly arrested.

Had DNA testing existed back then, Worrell would have been a sitting duck, say prosecutors Martha Bashford and Melissa Mourges of the Manhattan DA’s cold-case DNA project.

“The irony is, the case is much stronger now than the day after it happened,” Mourges said.

Back then, a series of judges’ decisions allowed Worrell to allegedly pursue his lust for rape over the next three decades – typically staking out his victims for hours, covering his face, then prying open their windows and attacking at knifepoint.

First, a Manhattan judge let him out on $5,000 bail. Then, after he attacked and shot a woman in Hollis, Queens – for which he was convicted by a jury in 1975 – an appeals panel, citing a technicality, voided both that conviction and his admission to the Manhattan rape. Astoundingly, a Queens judge then let Worrell out on bail a second time, pending retrials on the two attacks. He promptly vanished.

Worrell would be a fugitive for the next three decades, living in Washington and Georgia, and even spending the ’90s as an Arabic scholar and translator in Egypt. All the while the tell-tale green panties sat in the Manhattan DA’s archive in Queens.

Fast forward to last year. Worrell, living in Georgia under the name Omar Abdul Hakeem, applied for a shotgun permit. A background check revealed Manhattan and Queens still considered him a fugitive, and he was extradited back to the city.

Bashford and Mourges, preparing for a possible retrial, dug up the 1973 case from the archives. Inside the file’s cardboard accordion folds they found Worrell’s old mug shot, grisly photos of the knife-slashes on the victim’s neck – and the stained panties.

Worrell, who now faces life in prison, remains on Rikers Island, pending a May 17 court date.

As for the actress he allegedly raped, “She was extremely grateful,” Morgenthau said.

Relief, too, was felt by the victims of the so-called “Silver Spring rapist” – more than 20 Washington-area women who have been told Worrell is now behind bars.

“Each of the women has been contacted,” said Lt. Eric Burnett, a police spokesman in Montgomery County, Md. Worrell’s lawyer, Michael Rubin, declined to comment upon the case except to call his client a respected Arabic scholar who believed his Manhattan and Queens cases had been resolved and was unaware that he was a fugitive.

June 26, 1973: Knifepoint rape of a 25-year-old artist and actress in her W. 21st St. bedroom

June 28, 1974: while out on bail, commits a gunpoint attack on two women in Hollis, Queens – one of whom he tries to rape

1987 to 1991: Twenty-one attacks in the Washington, D.C. area (in Silver Spring, Chevy Chase and Bethesda). The then-unidentified attacker earns the name “The Apologetic Rapist” for apologizing to his victims after violating them. He’s also called the “Silver Spring Rapist.”

1993: Attacks two women in separate incidents in Morris County, N.J.

* Authorities dug up the 1973 case. Inside the files, they found Worrell’s old mug shot, grisly photos of the knife slashes on the victim’s neck, and a pair of green panties.

* DNA evidence found on the underwear helped investigators link Worrell to the crimes